Three people have died in a six-vehicle collision on Interstate 35, involving two passenger cars and four 18-wheelers

The fatal crash took place around 2:30 p.m. on Tuesday afternoon, on the northbound lanes of I-35 in Waco, Texas, underneath the Valley Mills Drive overpass.

The exact cause of the crash is currently under investigation however truck driver Harry Turner, who was involved in the crash, told reporters that he believes two speeding cars may have sparked the incident.

“The cars were speeding in traffic when one clipped another, causing the car to collide with his eighteen-wheeler,” local KWTX.com reported.

Some of the vehicles involved caught fire after the impact. Interstate 35 was shut down in both directions immediately after the accident.

Three people were reported dead, but their identities have not yet been revealed.

Police say the Valley Mills Drive overpass will remain open, but will need to be tested for structural damage due to the intense heat and smoke from the crash.

The southbound lanes of Interstate 35 reopened around 5:30 p.m., however northbound lanes are expected to be closed overnight.